Besides for the fact that all the cool kids are doing it? Here's why:

• They're slimming:  Black = slim, and tights are no exception. Black tights automatically make your legs look slimmer.
• They elongate your legs: Especially when paired with black shoes, they make your legs look like they just keep going, making you look taller. Going totally monochromatic, while possibly slightly morbid-looking when that color is black, heightens the effect.

Time to bring black tights out from their exile and place them back on the fashion pedestal right next to their bolder, patterned counterparts. Check out a few of your best options here!